Ice-volume changes (1936–1990) and structure of Aldegondabreen, Spitsbergen

Abstract

Aldegondabreen is a small valley glacier, ending on land, located in the Grønfjorden area of Spitsbergen, Svalbard. Airborne radio-echo sounding in 1974/75, using a 440 MHz radar, revealed a polythermal two-layered structure, which has been confirmed by detailed ground-based radio-echo sounding done in 1999 using a 15 MHz monopulse radar. The 1999 radar data reveal an upper cold layer extending down to 90m depth in the southern part of the glacier, where the thickest ice (216 m) was also found. A repeated pattern of diffractions from the southern part of the glacier, at depths of 50–80 m and dipping down-glacier, has been interpreted as an englacial channel which originates in the temperate ice. From joint analysis of the 1936 topographic map, a digital elevation model constructed from 1990 aerial photographs and the subglacial topography determined from radar data, a severe loss of mass during the period 1936–90 has been estimated: a glacier tongue retreat of 930 m, a decrease in area from 8.9 to 7.6 km2, in average ice thickness from 101 to 73 m and in ice volume from 0.950 to 0.558 km3, which are equivalent to an average annual balance of –0.7 mw.e. This is comparable with the only available data of net mass balance for Aldegondabreen (–1.1 and –1.35m w.e. for the balance years 1976/77 and 2002/03) and consistent with the 0.27˚C increase in mean summer air temperature in this zone during 1936–90, as well as the warming in Spitsbergen following the end of the Little Ice Age (LIA), and the general glacier recession trend observed in this region.

Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar

“…The long-term mass balance of the glacier (in metres water equivalent per year) was calculated using the measured surface lowering and an average of the glaciated area, and was found to be −0.6 ± 0.2 m/yr. This figure is close to the −0.55 m/yr for Svalbard glaciers as a whole, and glaciers of comparable size and geometry, such as Austre Brøggerbreen (5 km (4 km 2 , −0.55 ± 0.45 m/yr) and Aldegondabreen (7.6 km 2 , −0.7 m/yr) (Hagen et al, 2003b;Navarro et al, 2005).…”

“…4, 5 and 6. At the LIA maximum (approximately 90 years ago; (Hagen et al, 2003a;Hodgkins, 1997;Navarro et al, 2005)), the glacier had a volume of 0.47 km 3 , compared with 0.42 km 3 in 1936-38, and less than 0.2 km 3 in 2009. Thus, in a period of less than 100 years since the end of the LIA Tellbreen has lost some 60-70% of its total volume and the glaciated area has been reduced by more than 50%.…”

Recent Deceleration of the Ice Elevation Change of Ecology Glacier (King George Island, Antarctica)

“…Ice elevation changes were computed by differencing subsequent DEMs for each time interval (e.g., [54][55][56]). Each DEM was interpolated into a common reference system and grid, co-registered with use of several GCPs derived from the 2016 TLS DEM.…”

Mass change study on Arctic glacier Pedersenbreen, during 1936–1990–2009

“…The ablation reached a maximum value of 60 m in the tongue area of 1990's morphology. On the upper accumulation zone of high elevation, ice was thickened, which was consistent with the changing trends of some other glaciers in Svalbard [24]. The accumulation zones and ablation zones, as well as the amount of accumulation and ablation of the corresponding years are counted in Table 4.…”

“…Harbor inferred that the maximum cross-sectionally averaged erosion rate is 5 mm/a from a simulation [23]. Usually the subglacial topography is considered not to have changed much in 100 years, and the influence of bedrock changing upon the glacier volume estimation can be ignored [24]. Because this study involves a time span of 73 years, we use the subglacial topography obtained in 2009 for 1936 and 1990.…”